U.S. patent application number 10/539617 was filed with the patent office on 2006-07-20 for echo suppression for compressed speech with only partial transcoding of the uplink user data stream.
Invention is credited to Christopher Beaugeant, Renato Beluffi, Tim Fingscheidt, Herbert Heib, Bernd Jager, Luca Prati, Herve Taddei.
Application Number | 20060160581 10/539617 |
Document ID | / |
Family ID | 32338070 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060160581 |
Kind Code |
A1 |
Beaugeant; Christopher ; et
al. |
July 20, 2006 |
Echo suppression for compressed speech with only partial
transcoding of the uplink user data stream
Abstract
Disclosed is a method for suppressing (10) echo (z(t)) in uplink
data (y(t), 12-16) originating from a terminal (2, 3), said method
allowing a delay and a decrease in quality during echo suppression
of uplink data originating from a wireless terminal (2, 3).
According to the inventive method, original or copied downlink data
(12-16) and uplink data (19-21) are analyzed in order to prepare
echo suppression (10), and uplink data (19-21) is modified in the
compressed state in order to reduce echo (10) by using the results
of said analysis (9) of the downlink data (12-16) and uplink data
(19-21).
Inventors: |
Beaugeant; Christopher;
(Munchen, DE) ; Beluffi; Renato; (Milano, IT)
; Fingscheidt; Tim; (Munchen, DE) ; Heib;
Herbert; (Puchheim, DE) ; Jager; Bernd;
(Munchen, DE) ; Prati; Luca; (Ferrara, IT)
; Taddei; Herve; (Munchen, DE) |
Correspondence
Address: |
MORRISON & FOERSTER LLP
1650 TYSONS BOULEVARD
SUITE 300
MCLEAN
VA
22102
US
|
Family ID: |
32338070 |
Appl. No.: |
10/539617 |
Filed: |
December 20, 2002 |
PCT Filed: |
December 20, 2002 |
PCT NO: |
PCT/EP03/14090 |
371 Date: |
January 10, 2006 |
Current U.S.
Class: |
455/570 |
Current CPC
Class: |
H04M 9/082 20130101 |
Class at
Publication: |
455/570 |
International
Class: |
H04B 1/38 20060101
H04B001/38; H04M 1/00 20060101 H04M001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2002 |
EP |
02028587.0 |
Claims
1. Method for suppression (10) of echo (z(t)) in uplink data (y(t)
1216) coming from a terminal (2,3), with the original or a copy of
the downlink data (12-16) and uplink data (19-21) being analyzed to
prepare for echo suppression (10), and with uplink data (19-21) in
compressed state being modified for echo reduction (10) using the
results of the analysis (9) of the downlink data (12-16) and of the
uplink data (19-21).
2. Method in accordance with claim 1, characterized in that the
non-transcoded state represents the compressed encoding in which
the uplink data was transmitted compressed over a mobile radio
network.
3. Method in accordance with claim 1, characterized in that, before
the analysis (9), the downlink data (12-16) and the uplink data
(19-21) is decoded (18) partly or entirely from the transcoded
state into a format representing the timing sequence of the signals
representing the data (e.g. TDM).
4. Method in accordance with claim 1, characterized in that a copy
is made (17a, 17b) of at least downlink data (12-16) to be sent in
the direction of the terminal or the original of the downlink data
is sent to the terminal, while the other downlink-data (original or
copy) is used for encoding (18) and analysis (9) to make possible
echo reduction (10) in the uplink data, with only either copy or
original of the downlink data being decoded.
5. Method in accordance with claim 4, characterized in that the
downlink data and the uplink data will be copied before the
analysis.
6. Method in accordance with claim 1, characterized in that, during
echo suppression (10) general knowledge of relationships between
downlink data and required changes in uplink data is also taken
into consideration for echo reduction on the uplink data using the
results of the analysis (9) of the downlink data.
7. Method in accordance with claim 1, characterized in that the
terminal (2, 3) is a mobile radio terminal.
8. Method in accordance with claim 7, characterized in that the
terminal is a mobile radio terminal for a cellular mobile radio
network.
9. Method in accordance with claim 1, characterized in that the
propagation delay caused by the partial decoding of the uplink
stream is less than it would be with a complete decoding of the
uplink stream, subsequent echo suppression and subsequent
re-encoding.
10. Device (11) for echo reduction, especially for executing the
method in accordance with claim 1, with a decoding device (18) for
transcoding of downlink data to be sent to a terminal or sent to a
terminal and of uplink data coming from a terminal into a format
representing the timing sequence of the signals representing the
data (e.g. TDM), with an analysis device (9) for analysis of the
transcoding (18) data for an echo reduction of uplink data with an
echo reduction device (10) to reduce the echo in uplink data in the
non-transcoded state coming from a terminal.
Description
[0001] The invention relates to method and to devices for
suppressing echo in uplink data originating from a terminal.
[0002] In different telecommunications networks (especially
cellular mobile radio networks such as GSM, UMTS, 3G, CDMA-based
networks and other networks) an echo can occur in data sent from a
terminal in the direction of the mobile radio network, which can
arise by virtue of the fact that, at the terminal, acoustic signals
output by a loudspeaker (which are based on downlink data
transmitted from the network to the terminal) are picked up in more
or less weak form by the microphone of the terminal. The microphone
of the terminal thus receives acoustic signals from the user
currently using the terminal by speaking into it (or using the
mobile radio terminal in some other way) and in addition a weak
interference noise in the form of the component (arriving as
downlink data from the network at the terminal) reproduced by the
loudspeaker of the terminal (of a party to the call or of their
environment) of the terminal user. The voice data of the terminal
user picked up by the microphone and the additional (noise) data
picked by the microphone which a microphone in or for the terminal
has picked up, is transmitted jointly to the other party in the
terminal user's call so that in addition to the voice signal of the
terminal user, the latter hears his own words as an echo (that is
the speech sequence of the terminal user's other party in the call
which was transmitted from the latter to the loudspeaker of the
terminal, to the microphone and from the microphone via the
terminal etc. back to the other party).
[0003] To counter this effect echo cancellers=echo compensators)
are proposed in mobile radio networks (known for example from
www.etsi.org etc. or Jacek Biala "Mobilfunk and intelligente Netze
(mobile radio and intelligent networks)", Vieweg-Verlag, ISBN
3-528-15302-4, pages 109, 127 and 344). In a switching device of a
mobile radio network the data arrives for example via ATM-AAL-2
data connections or other data connections, with the data being
encoded into a mobile radio codec format (especially AMR format)
for compressed transmission especially over the air interface. For
echo cancelation the speech encoded into the codec format
(compressed state) is transcoded into a format which represents the
speech over the course of time, such as the TDM (Time Division
Multiplex) format (i.e. converted as regards its encoding) and the
echo (of the downlink data) contained in the uplink data coming
from the terminal is reduced as far as possible by taking account
of the downlink data in the uplink data (echo cancellation). By
avoiding this echo the speech quality is significantly
improved.
[0004] The object of the present invention is, with a reduction of
the echo in the uplink data coming from a terminal, to optimize as
efficiently as possible the delay in data caused by echo
cancellation. This is achieved by the objects of the independent
claims in each case.
[0005] By transcoding the original or a copy of compressed data to
be sent to the terminal (downlink data) and data coming from the
terminal (uplink data) completely or partially (into TDM format
etc) and analyzing this data received for reduction of the echo in
non-transcoded uplink data for this coming from the terminal, a
delay in the data during echo cancelation is efficiently avoided
and/or a reduction in the speech quality through transcoding of
data coming from the terminal is lessened.
[0006] Further features and advantages of the invention are
produced by the claims and the subsequent description of an
exemplary embodiment on the basis of the drawing. The Figures
show:
[0007] FIG. 1 a schematic diagram of how an echo is known to
arise,
[0008] FIG. 2 a schematic of echo cancelation in accordance with
the invention,
[0009] FIG. 3 the data streams for echo cancelation in accordance
with the invention.
[0010] FIG. 1 shows a user 1 of a terminal (not shown) comprising
items such as a microphone 2 and a loudspeaker 3 which (2,3) for
example is located in a vehicle or in a room 4. The loudspeaker 3
belonging to his terminal (for example also connected via a headset
or a handsfree automobile device to the terminal) receives via a
mobile radio network, known per se but not shown, and a terminal
downlink data x(t), to be output acoustically which propagates in
the vehicle or the room 4 and is also picked up as interference
noise z(t) by microphone 2 of the terminal (or for the terminal).
The microphone 2 of the terminal thus receives strongly or weakly
(downlink) data sent by the partner in the call of user 1 and
output by the loudspeaker 3 as well as data s(t) output by the user
1 of the terminal (2, 3) as speech etc. and transmits the sum etc
of the data (recorded inadvertently by loudspeaker 3 and
deliberately by user 1) as signal y(t) in a known way via a mobile
radio terminal, an air interface etc, to the mobile radio network
and onwards to the other party in the call of subscriber 1. The
other party in the call of the subscriber 1 therefore perceives an
echo of his words which is to be suppressed since it reduces the
speech quality.
[0011] FIG. 2 shows how, through echo cancellers, the downlink data
x(t) to be transmitted or transmitted by the other party 5 in the
downlink 6 via a mobile radio network, an air interface etc. to a
terminal with a loudspeaker 3 is used for echo reduction.
[0012] The downlink data x(t) transmitted over the downlink 6 can
be copied and in a copy (or in the original) independently of the
transmission of the original (or of the copy) transcoded partly or
completely in the direction of the terminal 2,3 in an echo
equalizer 7 and analyzed and used for reduction (10) of the echo
(8) in uplink data originating from the terminal 5 after an
analysis (9). The same applies to the uplink data.
[0013] In accordance with the invention the downlink data x(t) to
be sent to the terminal (in the original or its copy) and the
uplink data x(t) coming from the terminal (in the copy or in the
original) is transcoded (entirely or partially) and thereafter the
modified data is analyzed (9), with the result of the analysis
being used for echo cancelation. An echo reduction in
non-transcoded uplink data avoids a deterioration (otherwise partly
caused by a transcoding) of the speech quality and/or a delay.
Empirical values can be obtained from analysis of downlink data and
of uplink data containing an echo this data, giving details of how
the uplink data can be changed without transcoding it (into a
format representing the timing, e.g. the TDM format) after an
analysis of transcoded downlink data, in order to reduce the echo
of the downlink data in the uplink data in this way, which is
possible as a rule by modifying a number of bit values in the
uplink data which contain the echo of downlink data. In this case
for example simplified times and amplitudes of acoustic sequences
in transcoded downlink data and times in the non-transcoding uplink
data can be taken into account. together with empirical values
relating to times at which an echo of the downlink data of another
time appears in the uplink data.
[0014] FIG. 3 shows how downlink data 12-16 to be sent to a
terminal in a downlink 6 and uplink data 19-21 is copied by a
copying device 17a, 17b, sent in its original form or (as here) as
a copy to a decoding device 18 for encoding (transcoding into a
format representing the time sequence, e.g. the TDM format), at
which point it is analyzed by an analysis device 9, with the result
of the analysis being able to be used by an echo reduction device
10 to reduce the echo in data 19-21 coming over an uplink 8 from a
terminal, without transcoding this uplink data 24 (or alternatively
its copy) for this purpose. The analysis device (9) analyzes the
transcoded (18) downlink data and uplink data for an echo reduction
of the uplink data. The uplink data 22 modified in the echo
reduction device 10 for echo reduction is forwarded via the uplink
indicated by the arrow 8 in the direction of a receiver via one or
more telecommunications networks.
* * * * *
References